Drill bit



June 13, 1933. Q

C. K. HOLT-.ET AL DRILL BIT Filed April 8, 1930 2 Sheets-Sheet l 1/ [Glam M41 in various kinds of earth formations, and

Patented June 13, 1933 PATENT OFFICE orrnarins K. nor/r nun 101m 3. 1133mm. or-.;sA1v'r A BARBARA, GAIiIFORNIA DRILL BIT y I Application med A ril s, 1930. serial No. 442,667.

This invention relates to a weil bit for use in the rotary method of well drilling, and has for one of its objectsto provide abit of this character which is adapted for use which is operable to penetrate the earth formation as the result of a true cutting action as distinguished. from a scraping action. 1

Another object of. the invention is to provide a drill bit of the character stated which a handle the circulating fluid in a manner to maintain its cutting parts free of the cut tings. i i

he invention has for a further object to provide a drill bit of the character stated which does not wobble or have undesirable motion in the hole being drilled, and which is adapted to drill a straight hole of uniform gauge. With the foregoing and other ob ects in new, the nature of wh ch Wlll appear as the description proceeds, the invention consists in the constructlon, combinatlon and arrangement of parts hereinafter fully described and claimed, and illustrated in the accompanying drawings, wherein: Fig. 1 is a view in side elevation of a drill bit constructed in accordance with our invention. Fig. 2 is a bottom plan view of the drillbit. Fig. 8 is a viewpartly in vertical section and partly in side elevation of the drill bit. Fig. 4 is a sectional View taken on the vertical plane indicated by the line 44-ol? 2. Fig. 5 is a sectional view taken on the vertical plane indicated by the line 55 of Fig. 2.

The bit provided by the present invention includes a shank 1 and a cutter head 2 on the lower end oil the shank. The shank 1 is ends stepped downwardly and outwardly provided at itsunner end with an external- 1y screw-threaded pin 3 to facilltate its connectionwith a drill collar, or the like, on

{the lower end of a drill stem or drill pipe. The head 2 is provided with arms 4 which extend radially outward therefrom and a-re equally spaced, and it is provided with a plurality of like series of cutters 5, 6 and 7 The cutters 6 and 7 of each series are "aligned and extend substantially radially center of the head 2.

outward from the axial center of the head 2. The cutters 5 which are the outer cutters are provided at the outer ends of the arms 4, and extend from the upper ends of the arms to points below the arms. The cutters 5 areof' arcuate formation in horizontal-cross section, and have their convex sides arranged forwardly, or in the direction of the rotation of the bit, to provide outer vertical cutting edges 8. The cutters 5 are reinforced at their rear sides with central longitudinal ribs 9 and are provided at their lower ends with cutting edges inclined or curved upwardly and inwardly.

Theinner cutters 7 and the intermediate a cutters 6 aresimilar in shape, and the former extend downwardly from the lower end of the head 2, and the latter project downwardly from the lower: sides oi the arms 4. The cutters 6 and? are of hollow triangular formation or of V shape in cross and 7 have their lower ends 11 inclined upwardly and rearwardly. The cutters 5, 6

a and 7 of each series are equally spaced, and

the inner cutters? of'the respective series are eq ally spaced aboutthe longitudinal Like cutters 12 project downwardly from the lower end of the head 2 between the inner cutters 7 and are arranged at opposite sides :of the axial center of the head. The cutt'ers 12 maybe spiralled and may be comparatively short. The cutters 7 extendbelow the cutters 12, the cutters 6 extend'b'elow the cutters 7, and the cutters 5 extendbelow the cutters 6. In other words, the cutters 12, 7, 6 and 5 have their lower-9 from thevertical axis of the bit. a a The shank 1 isprovided with a longitudinal fluid passage 13 WhlCl1C0lI1Il11U1l- I cates at its lower end with branch ports 14. The ports 14L pass through the head to dis charge from its lower endfat points forwardly of and adjacent theinner cutters 7. The passage 13 also communicates with a port 15 discharging downwardly between 1% er than the front portions thereof with the 5 result that the cutters will remain sharpened until completely worn away. As the cutters of each series thereof are relatively spaced, and due to the manner in which the circulating fluid is delivered to the hole with respect to the cutters, the cutters are effectively washed and kept free of cutters. Furthermore, the spacing of the cutters ofv the respective series permits them to pass through loose earth formations without becoming clogged. I r

The downward and outward inclination ofthe cutters causes the bit to cut in a coring manner, with the result that a straight hole of even gauge will be drilled; All parts of the tool may be cast integral, and the active edges of the cutters may be hardened or provided with hard cutting material. I

While we have described the principle of the invention, together with a typical embodiment thereof, it is to be understood that the structure shown is merely'illustrative and that various changes may be made when desired, as fall within the scope of the invention as claimed.

lVe claim: v

1. A drill bit having a plurality of series of downwardly extending cutters, the cutters of each series being relatively spaced and extending outwardly from the axial center of the bit, the outer cutter of'each I tween and shorter than the inner cutters and the bit being provided with a circulating fluid passage discharging at points in advance of the cutters.

2. A well bit of the character described including, a head, spaced radially projecting arms on the head, and a plurality of series of downwardly projecting cutters, each series including an outer cutter of arcuate cross section at the outer end of an 31'11'1, an intermediate cutter of V-shaped transverse cross section on the arm, and an inner cutter of V-shaped transverse cross section on the lower end of the head, the intermediate and the inner cutters having their open sides facing rearwardly whereby they remain sharpened during use, the lower ends of the cutters being stepped downwardly and outwardly relative to the longitudinal center of the head.

In testimony whereof we hereunto affix our signatures.

CHARLES K. HOLT. JOHN B. MERRITT. 

